The researchers also measured the amounts of nitric oxide in both cancerous and normal cells to see how well they had been able to target the gene therapy. Encouragingly, they found that production of the molecule had only been enhanced in tumour cells and the cells immediately surrounding them.

Professor Hirst adds: "Many scientists researching gene therapy use viruses to deliver genes to cells. We tried a different approach “ using tiny spheres of lipid called liposomes, which interact in a natural way with the lipids in a cell's membrane. Each method of delivery has advantages and disadvantages and extensive research on each will tell us which will work best in patients."

Hirst and his team believe that the technique will be ready for testing in patients after some further refinement. They are also testing whether the technique enhances chemotherapy as well as radiotherapy.

Professor Robert Souhami, Cancer Research UK's Director of Clinical and External Affairs, says: "Cancer is a complex disease and we need imaginative approaches to combat it. Using a switch turned on with a precisely directed x-ray beam is one such approach, and holds promise in targeting treatment towards cancer cells and avoiding healthy cells.

"Cancer Research UK is researching a wide range of gene therapies in order to harness the technique's full potential against cancer." cancerresearchuk